1. Field of the Invention
The invention relates to valves; and, more particularly, to back flow preventing valves which prevent backflow to avoid contamination of the supply fluid.
2. Description of the Prior Art
In my prior U.S. Pat. No. 3,724,487, I disclosed a backflow preventing valve for preventing the flow of fluid from the outlet passage back into the inlet passage, even under conditions which normally cause fluid backflow such as back pressure or siphonage.
In the valve of the present invention, I disclose inlet and outlet check valves which open and close in an improved manner. It is desirable that such check valves have the necessary force for positioning and securely closing the check valve without providing undue resistance to the continued opening of the check valve after reaching an initial open position.
Futher, in accordance with the present invention, I disclose an improved diaphragm operated relief valve having a resiliently mounted valve member movable with relation to the diaphragm. In my prior patent, the exemplary diaphragm is coupled by spring means to the movable valve member. In order to replace such diaphragm or otherwise service the interior of the relief valve housing, it may be necessary to disconnect the diaphragm from the spring connection to the valve member and related components. In addition, in my prior patent, the relief valve seat means normally would remain stationary with minor flexing of the diaphragm under slight variations in fluid pressure. In the valve of the present invention, the slight flexing of the diaphragm does not cause the outlet exhaust passage to open.